Protractor.



J. E. SMITH.

PROTRAGTOR.

APPLIUATION FILED JAN. 7, 1910.

977,048. Patented Now/.29,1910

JAMES Emiliov SMITH, or URBANA, ILLINOIS.

rno'rnAo'roR.

Application filed January 7, 1910. Serial No. 536,930.

To all wlw/omit 'may concern:

Be it known that I, JAMES ELMo SMITH, a citizen of the United States, and resident of Urbana, county of Champaign, State of Illinois, have invented certain new and useful Improvements in Protractors, of which the following is a specication.

This invention relates to protractors which are adapted for plotting and measuring the directions of lines.

One of the objects of this invention is to construct an instrument by means of which the directions of lines may be plotted and measured by any of the following methods: arcs, trigonometric functions, latitudes and departures, rectangular cordinates, ings, azimuths.

Another object is to construct an instrument which will combine the functions of the usual triangles, squares and protractors.

Further objects will appear in the detailed description.

The invention will be described in connection with the accompanying drawings, in which;

Figure- 1 is a plan View of the instrument; Fig. 2 is a perspective view of the protractor arm and its pivot and clamping means, the parts being separated, andylfig. 3 is a section along the line 3-3 Fig. 1, in which the arm is swung to a position at right angles to the lower edge. Fig. Llis a plan view showing al is cut away forming an inner edge 14, which is the arc of a circle, and edges 15 and 16.

A fiat over-hanging plate 17 'is secured to Y.

In the the base in any suitable manner. specific construction shown, this plate is secured by means of screws; it is obvious, however, that the plate may be secured to the base in any other manner, for instance, it may be brazed, soldered or even spot welded thereto. The plate 17 is provided with a bearing aperture A18, for a purpose hereinafter to be described.

An arm 20 has permanently secured to its upper face a threaded bearing ring 21, which is arranged to be journaled in the bearing aperture 1S. A clamping ring, or nut, 22 has a threaded engagement with the bearing ring 21 so as to clamp the ring and arm in position on the base. By means of make it as light as beartheabove construction the arm 20 is ar- Specication of Letters Patent. Patented NOV. 29, 1910.

ranged to move in the open-space of the base with its lower face in the same plane as the lower face of the base. An extension 23 is arranged tober4 clamped to the arm by means of. screws 24 engaging the threaded holes 25 in the arm. The part'20 and the extension 23 coperate to form a single arm, and the part 20 is of the same thickness as the base and thus the extension 23 will lie on the upper face of the base of the instrument. The base iscut away at 26 so as to possible.

The plate and the base of the instrument are provided with a graduation mark 29, which is opposite the pivotal point 27 and the zero on the edge 11. The arc 14., which is struck from the pivotal center 27 of the arm 20, is graduated in degrees or fractions thereof. The graduations on the edge 14. are provided' with three rows of reference characters. In the inner row the zero is placed at the upper portion of the scale, the graduations running right and left from 0 to 90. In the second row the reference characters run from Oto 180, the zero being placed opposite the 90 of the first row. In the thirdrow the reference characters run fromv 180 to 360, the 180 being placed opposite the zero of the second row. The reference characters in the second andthird rows are placed parallel to theedges 12.and 13 respectively, and the reference characters at any point are inversely arranged so that the second row reads normally when the instrument sets on the edge 12, while the third row reads normally when the instrument sets on the edge 13.

The outer edges 11, 12 and 13 are graduated in any suitable units. for instance, in inches or centimeters, and to any suitable scale, the zeros of these graduations being opposite the pivot center 27,` so that the pivot center is located at the intersection of lines dropped from the zeropoints. The graduations extend from zero to 10 at the intersections of the edge 11 with the edges 12 and 13. The edge 15, which is preferably beveled as shown, and which is located on the line between the pivot l A)int 2T and the zeros on the edges 12 and 123. is graduated in the same units as tht` edges 11, 12 and 1S, the aero being at the pivot point 27.

The edge 28 of the arm 2t), which is preferably beveled, is graduated in the same tance between the edges 15 and 1G is equal to the width of the arm 20, so that the arm 20 can be moved to position its edge 2S in alinement with the edge 15. so that edges 15, 28 and 29 may form a continuous scale edge.

The operation of the instrument and its use will now be described.

The direction of lines by means ot arcs may be readily obtained from the scale on the edge 14. lhen a trigonometric funetion of the angle is given, the direction ot the line may also be readily laid oit, for instance, if the tangentI oit the angle is given, the arm is moved until the graduated edge 29 coincides with the graduation on one ot the edges 11, 12 or 13 corresponding to the natural tangent. The proper scale which must be used will depend upon whether the first, or the second and third rows of figures on the arc are used. ln Fig. 1 if the first row is used the angle will be 30o, and it will be seen that the position of the edge 29 on the graduated edge 11 corresponds to the natural tangent of the angle of 800. Similarly, since. the natural vsecantis the distance between the pivot point 27 and the point where the edge 29 intersects one of the edges 11, 12 or 13 the angle can be readily laid off by swinging the arm until the proper graduation on the edge 29 is in alinement with the proper edge. For angles greater than 45o the co-tangents and natural co-secants can be used; in this Way the dimensions of the instrument can be kept down. The position of the arm may also be located it the sine or cosine of the angle is known. .[his may be accomplished by ruling lines upon the drawing paper, or by laying a straight edge parallel to the edges 11, 12 or 13, and moving the arm until the graduation 10 coincides with the straight edge. The parallel position of the straight edge may be easily obtained by means of the graduations on the edges. The arm can similarly be located if the versed sine or the co-versed sine are given. The above operations can also be reversed and the functions of angles measured. I t will thus be seen that the directions ot' lines may be plotted and measured on a surface underneath the protractor it'. the natural trigonometric functions of the angles are given. It is obvious, however, that the edges 11, 12 and 13 may be provided with logarithmic graduations as shown in Fig. 1 so that the arm may be properly located if the logaritluns ot' the trigonometric functions are given. '.l`he bmly or base ot the instrument is cul away so as to leave the interior ot' the protr; ltor open t'or plotting and measuring. ln this way also the are 1-1 can be made large and, therefore, the graduations may be made very ne.

The construction of the open ring 21 enables the drattsman to use the pencil inside of the ring so that the position of. the center may be readily determined. The center can also be easily marked by ruling along the edge 2S inside of the ring, and then shifting the arm and ruling another line crossing the ti'rst.

The rectangular instruction of the trame renden-1` it convenient. since the edges may be used for the same purpose as the edges of the ordinary right angle triangle, the arm 2S being used to lay oill angles other than right angle-s.

vThe rectangular construction ot the protractor also makes it convenient to orient. This is of special signilicauce when plotting a traverse line by azimuths or by coordinates where the protractor must be frequently moved and reset. The successive points may be reached by sliding the protraetor along a. T-square, then along another straight edge aty right angles to the T-square until the point is reached. The orientation of the instrument is thus maintained and no time is lost in orienting at each point.

lVhen plotting by latitudes and departures, or by coordinates, the distances may be plotted directly by means ot the scales almig the edges ot' the trame. Bearings ot lines are plotted by using the inner' row ot tigures along the are, the zero at the top of the pro` tractor are representing a point upon a meridian. A line having a bearing of north 30o east, would be plotted by drawing a line from the center toward a point 300 to the right, of zero.

The azimuth of a line being its direction as referred to some other line of reference, usually a meridian, the angle made with this reference line is measured clockwise, and continuously from either the north or the south'from zero to 360. For example, a line whose bearing is N. 30 E. has an azimuth of 210o when south is considered aS the starting point or Zero. The protractor may be graduated to show azimuths either from the north or from the south. In the drawing the azimuths are shown as starting from zero at the south. The outer rows of figures upon the arc are so placed that they cannot be read unless the protraetor is set up upon its proper end for reading azimuths, and hence must be read correctly. In addition this arrangement ot figures enables one to determine easily and approximately the functions ot' angles greater than 900.

. By inea hetn'een the'afrln Q!) and its'extension-Qf, the prot raetor may be 4provided :With iai number off ditlerent'sizedfextensionsso that the-prt tractor 4maybe used-for diterentisized work..l A numbei` of arms withdift'erent scalesmay also'. be 'used interchangeably.' "'tlh'e a'rml 20,

which is Wholly inside'oftheopenspacehas its lou-'er face" located" infthe samel plane-fas the'lox'ver fa'e'e ofthetrasera-nd this` together with :t beveled constructionfof'-the edge-2S,"

enables the directions of lineson a surface underneath the protraetorffto/bef accurately plotted and measured.' Siniila1'ly,t.lie .edge fl engages audi 'contacts with the graduated edges 11. '12; 13' and 14, andthus the: angle ma v'be vaee'urately plottedand measu're'dx The elamping'ring 9 2 forms a very conf .'enient' clamping'fdevice-*n viex'v ofthe fact that it "is fout" of the -d'ra ftsm'an's .vly4 'and 'allows the interior of the bearingiiring 21 aud'the portion of the scale iocatedltherein t he clearly visible` y l It'"\i fi`ll 'thus be seen-thatf-ithis` invention p'i-'ovidcs a' h""very- 1convenienti#instrument,

ix-hielt combines Vth'e'-funei't-onjsgtof:zthe usual tria l iglesa'nd protraetorgl and also 'Jenables' suitable' material'.

t :"'T-he 'term` basei'liue in t-hecla'imspis; tor he Vgtren its usual meaning, i." c., a referencelun. 'ln the instrument the edgesflO. 1'1, 12,-

lense being provided with trigonometric granhlatiens. and a protractor arm pivoted near the remaining edge at a point equidistant from uid graduated edges and eooper.xtin \rith all of said graduations. a portion of the hase between said pivot and graduatious heilig open, and the inside edge of said open space being provided with arc grmluat'imns.

L. protraetor comprising a base plate reetangular in shape and provided With a plurality el base edges. the outside edges` of said' hase being provided with equal graduationsthe graduations on one of said edges ns of bthe detach-able connection running in opposite directions from zero at its center toten at its intersections with the adjacent edges', and the gradnations on said adjacentedges runnin from zero.to ten at said intersections, an an arm Vpivoted o n said base -at theintersection of lines drawn frennsaid zero .points and at 4right angles to-.said edges, and coperating-with said graduations.

3. A protractor comprising a base plate reetz'i'ngularin shape. and provided with a plurality' of base edges, the outside edges of sa'idlbasefbeing provided with equaigraduations, the graduations on one oflsaid edges runningiu opposite directions from zero at itsfc'enter to ten at its intersections with the adjacent edges, and the graduations onsaid .adjacent edges rnnnino from zero. to ten 'at said intersections, anc an arm pivoted ou saidlbaseat the intersection of lines drawn from'said zero points and :itrightangles to said edges, and coperating with said graduations, said arm having equal gradnations thereon running from-zero at the pivotto- W'a'rd itsend, and in, the ,same unitsas said other gradnations.

n4. .A3 protractor comprising a b ase 'plate -rectangulanin shape, threeedges of said base being provided with graduationsan'd `amarm .p1voted;.nearthe remaining edge at -afipoint Leqnidistant rf rom said. three gradufate'd edgesga gportion of the 'base between said pivotanderaduations being open forin- 'zing'an inside geextending from said pivot .toward one ofsaid ed0es,said edge being providedogwith graduat1ons, said arm having a graduatededge arranged to be placed tinialinement with said inside edge. A v

m 5.141* protrae-tor comprising a base plate rectangular.)in, l shape, :three edges of said .base being'prov-ided with graduations, and an arm pivoted nearthe remaining edge at a edgesa portion of the base between said pivot and graduations being open forming an inside edge extending from said pivot toward one of said edges, said edge being provided with graduations, said arm having a graduated edge arranged to be placed in alineinent. with said inside edge, all of the graduations on said edges being in the same units. the zero on the outside edges being opposite the said pivot point and the zero on the inside edge and arm being at the pivot point.

(3. A protractor comprising a base provided with graduations and having an Open space therein, a protractor arm arranged to swing in said space to coperate with said graduations, and a pivot bearing for said arm comprising an overhanging portion Amounted on said base and provided with an aperture, a bearing lug on the upper fat-e of said arm and extending through said aperture and a clamping nut on said lug, where- -pointequidistant from said three graduated l Y. ring may. be visible.'

bv the lower face of said arm is arranged to "i lie, in thea plane of the lower face of said base."

,"'IJA vprotractor comprising a 'base provided with graduations, a swinging arm co operating with said graduations, and a pivot bearing lfor said arm comprising an over- ."f'hanging portionmounted on saidl base and provided with`an aperture and abearing l0 ring on the upper face of said arm and engaging said aperture, sald base 'being proi' 7 vided i'vi'thI an open portion fwhereby the lower fface of said arm is arranged to'lie in theplane of the lower face of sald base, and the, portion of the edge of ythe armv in the 8. Aprotractor comprising a base provided with'graduations, a'swinging arm coperati "with said'graduations, and apivot bearlng'for said arm comprising anjolverp I 4hanging portion mounted on said'ba'se and provided wlthan aperture, a bearing ringion the upper face of said arm and engaging said aperture, and anut having a threaded engagement with saidring'so as to clamp Y the arm'in position, said base being provided with'lan open portion whereby the lower-face of .said arm is arranged to' lie inthe plane of the lower face of said base, and the porti`on of the edge of thearm inV theiingrma'y bei"visible: A

A lp'rotra'c'tor' comprising a base prov 'i'fld wlth o operatin 'withtsaid'g'raduations andfa pivot bearin'g orsai'd armvcomprising a-iat overhanging plate secured ltothe upper face-of vsaid base and provided with anl aperture,

and a bearing ringon the upper face of said arm and engaging said aperture, saidbase being provided with an open portion Whereby'the lower face of said arm is arranged to lie in the plane of lthe lower face f of said base ``and the portion of the edge of the arm in the ring may be visible. 4 5

j ing an o'pen space therein and provided with 10.: A protractor comprising a base havaduations, a swinging arm cograduations, an arm pivoted to said base so as to move in said space and coperating gated extension forsaid arm arranged ,to be clamped thereto, said extension havingthe portion corresponding to `the lgraduations on the'armcutawavma;im l 12. A3 protractor comprising a base i reef tangu'lar in shape and-.having :a ,graduated arc with its diameter placedparallet toone oft-he edges ofthe rectangle-and sets ofref-v erence figures-,on saidbase-[running from' 0 to 180 and fromglSO-to 13670,.'the7 l.sets lbegin'- ning at -thefsame pointl and vrunning iin, lthe same directi0n,;' thex figures 5a-tany ,graduation pointbeing inversely arranged with "respect to each other, so that pue, set ,readsnorf mally wheniithe'fbase.setspion one edge .and

.the-other set-ireads-,normally when the r^`base vsets onvthe oppositeedga gA 13. i A lprotractor, comprisingaj base "rectangular, in shape i and providedawith a plurality of graduated n outsidedgasI and with :anropen space.; having...an inside .arc graduated edge, and. aA protracto'n arm; pivotedxonsaid base near Vone outside ,edge and at a point equidistant from lthe V,other outside edges and coperatingiwithall ofisaid 4'gradnations,l a .part of-:said armllng .in said open space lwith itsilower, fae in the plane of the-lower face of .said base. plate. l

: In testimony whereof I aiiix mvwsignature -in presence of two witnesses. Y f Y JAMEsfELMo-SMITH `Witnesses: r` 'R. N. FARGO, j- DAVID T..M1LES. ,i 

